This invention relates to filters, such as air filters for air-conditioning systems, and more particularly, to an air filter having a filtering element disposed in a frame with a support member on the downstream side of the filter element with the filtering element and support member being separated by a rib in the frame.
Filters, such as those used to filter air moving through ducts in air-conditioning and heating systems are well known. One common, inexpensive type of filter includes a filter element disposed in a cardboard frame. A support member for the filter element may be included. Such support members in these inexpensive filters may be made of light metal sheets with holes therethrough or similarly configured sheets of plastic. One disadvantage of these types of filters is that they are not durable and frequently will deform as a result of the force of the air flowing thereacross. This may result in gaps around the filters which allow air to pass thereby. This deformation makes such filters particularly hard to remove after use. Another disadvantage of these types of filters is that they are frequently made using adhesives. Such adhesives may emit fumes which get into the air supply and thus can contaminate air discharging from the airconditioning or heating system into the related building.
A solution to the deformation problem is to make more substantial air-filter apparatus which include a metallic frame and which use more substantial support members downstream from the filter elements. Air flow through these types of filters does not cause deformation. Therefore, gaps are not formed around the outer edges thereof, and they are easier to remove after use without knocking off dust and debris into the ductwork. However, some of these types of filters also use adhesives and have the resulting fume problem.
One known example of a filter having a metallic frame utilizes a square or rectangular frame formed of a metal member having a substantially C-shaped cross-section formed by an outer side and two, substantially parallel, inwardly extending legs which are substantially perpendicular to the outer side. Thus, an inwardly opening channel is formed in the frame, and the edges of a filter element are disposed in this channel so that the filter element covers a central opening through the frame. As the frame is being formed by bending a length of material into the square or rectangular shape, a support member for the filter element may be disposed in the frame. If the support member is left loose, it can sometimes cause difficulties in assembly of the entire apparatus, so the support member is usually fixedly attached to the frame, such as by welding or adhesives. A problem with welding is that it adds expense to the filter apparatus, and the problem with the use of adhesives has already been noted.
The present invention solves these problems by using an E-shaped cross-sectional shape for the material of the frame having an outer edge with a pair of inwardly extending legs perpendicular to the outer side and also includes a rib extending inwardly from the outer side and between the two legs. Preferably, the rib is parallel to the legs. When the frame is being formed, a support member may be disposed between the rib and one of the legs so that it is held in place without the necessity of welding or adhesives. The filter element is disposed between the rib and the other of the legs in a manner similar to that in the prior art. Thus, the present invention solves the problems of previous filters and the attachment of the metal support member and totally eliminates the need for adhesives.
The present invention is a filter apparatus, such as used in air-conditioning and heating systems for building. The filter could also be used in other applications where a filter is needed to remove foreign materials from flowing air or other gas.
Generally, the apparatus may be described as a frame apparatus for a filter. The apparatus comprises an outer frame with a central opening therethrough and defines an inwardly opening channel adapted for receiving a portion of the filter element therein, an inwardly extending rib disposed in the channel such that the filter element may be positioned to one side thereof, and a support member disposed in the frame and across the central opening on an opposite side of the rib from the filter element for providing support for the filter element. The frame has an outer side and a pair of inwardly extending legs forming the channel.
Preferably the legs are parallel, and the rib is parallel to at least one of the legs. The support member is held in the frame by the rib and one of the legs. Preferably, the rib is shorter than the legs. In the preferred embodiment, the rib and frame are integrally formed.
The support member comprises an expanded screen defining a plurality of generally diamond-shaped holes therein.
The frame preferably has generally parallelepiped configuration. In the illustrated embodiment, the frame is formed from a single piece of material having three bends, and the ends of the material are non-adhesively attached to one another, such as by riveting. In this embodiment, the material has a V-shaped notch formed therein adjacent to each of the bends such that a joint is formed by edges of the notches after the bends are made. The ends of the material overlap one another after the bends are made.
The frame is preferably made of a non-corrosive material, such as aluminum. The frame and support member preferably have smooth surfaces thereon to make the filter easier to install and remove and to protect the hands of users.
Stated in another way, the invention may be described as a filter apparatus comprising a frame defining a central opening therein, a filter element and a support for the filter element.
The frame has a substantially E-shaped cross-section with an outer side, a pair of legs extending inwardly from the outer side, and a rib disposed between the legs and extending inwardly from the outer side, thus forming first and second channel sections in the frame. The support is disposed across the central opening and has a portion disposed between the rib and one of the legs. The filter element is also disposed across the central opening and has a portion disposed between the rib and the other of the legs.
The filter element may be made of a tackified material. That is, it may have a tacky or sticky surface to increase its ability to trap foreign particles in the air flow, such as dust.
Numerous objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiment and the drawings illustrating such embodiment.